Filagra is another brand of medication used for the treatment of erectile dysfunction (ED), and it also contains sildenafil citrate as its active ingredient. Like other sildenafil-based medications such as Viagra, Suhagra, and Penegra, Filagra typically starts to work within 30 minutes to an hour after ingestion. However, individual response times may vary based on factors such as metabolism, health status, and whether the medication is taken on an empty stomach or with food.